The wolves of Yellowstone PublicDeposited

Descriptions

Historical records and intensive field surveys 1975-77
provided information on the population history, ecology, and
current status of wolves (Canis lupus) in Yellowstone National
Park and vicinity. Wolves occurred in unknown but seemingly
low densities during the latter 1800s in several areas of
Yellowstone where they were controlled periodically until 1926.
Populations apparently began increasing about 1912, primarily
in the northeast, and may have reached nonequilibrium levels
of 30-40 animals (postwhelping). Intensive control 1914-26
removed at least 136 wolves, including about 80 pups. During
this period Yellowstone wolves characteristically lived in
packs of 3-16 members, some of which followed the ungulates
in their seasonal migrations. Litters averaging 7.8 were born
in late March and April, primarily in the north central sector
of the park. Limited evidence suggests that elk (Cervus elaphus)
were important food for wolves during all seasons. Wolves either
survived the control era or moved in shortly thereafter for
singles, pairs, and a pack of four were reported the following
decade. Resident wolf packs, however, were eliminated from
Yellowstone National Park by the l940s. Large canids have
been sighted intermittently to the present, but their identity
has not been established. Singles and pairs comprised 89% of
116 "probable" reports over the past 50 years. Speculation
about factors limiting the Yellowstone wolf population considers
its relative geographic isolation from viable wolf populations
and possible genetic problems (including wolf-coyote hybridization)
associated with prolonged minimal population status. A
transplant of wolves from British Columbia or Alberta, or perhaps
Minnesota, is recommended to restore a viable population of
this native predator to Yellowstone National Park.